An imitation stone of high luster made of glass, paste, or gem quartz. (Merriam – Webster)
A bright, transparent artificial jewel that looks like a diamond and be sewn onto clothes. (Cambridge Dictionary)
Rhinestones are shiny, glass jewels that are used in cheap jewellery and to decorate clothes. (Collins Dictionary)
An imitation diamond, used in cheap jewellery and to decorate clothes. (Oxford Dictionaries)
Silver rhinestone pearl flower leaf pin brooch.
Rhinestone. Cambridge Dictionary.